1. Field of the Invention
The present invention relates digital video recording/reproducing apparatuses capable of performing playback in cue, review and other operations as well as handling digital broadcasting realizing interactive communications.
2. Description of the Related Art
1. Outline of Satellite Broadcasting System
1.1. State of Sending Radio Waves in Satellite Broadcasting
FIG. 1 is a simplified conceptual view showing a state of sending radio waves in satellite broadcasting. Radio waves from a ground station 2 are sent to a plurality of ground receivers (not shown) via a broadcasting satellite 4. The broadcasting satellite 4 sends out a plural numbers of transport streams TS1, TS2, TS3 and TS4. Each transport stream is distinguished from the others by its frequency, plane of polarization and other factors.
A plurality of services analogous to channels in terrestrial broadcasting SV11, SV12, SV13 and SV14 being packetized are multiplexed in the transport stream TS1 under a time sharing manner. Similarly, services SV21, SV22, SV23 and SV24, and services SV31, SV32, SV33 and SV34 are multiplexed respectively in the transport streams TS2 and TS3. Various control data representing indicative of program information, that of current time, control data needed for packetization and the like in addition to video data and audio data of each of the services are sent out to each of the transport streams. While, FIG. 1 shows only three transport streams, mamma more transport streams may be sent out. Furthermore, while FIG. 1 shows a total of four services multiplexed in each transport stream, in actuality many more services may be multiplexed therein.
1.2. Configuration of the Transmitter
FIG. 2 is a schematic illustration of a transmitter for generating and transmitting the transport streams described above. While, FIG. 2 shows only the transport stream TS 1 for simplicity, other transport streams TS2 and TS3 are generated thereby in the same manner.
Video/audio data ES1, ES12, ES13 and ES14 of the services SV11, SV12, SV13 and SV14 are provided to a video/audio data management part 7. The Video/audio data Es1, ES12, ES13 and ES14 are compressed by the video/audio data management part 7, and the resulting data are provided to a multiplex control part 9.
A multiplexing data management part 15 manages multiplexing of services such that which service should be multiplexed to other. The multiplex control part 9 provides services to be multiplexed to a multiplexing part 11 under the control of the multiplexing data management part 15. A control data generating part 6 generates a plurality of control data such as control data for multiplexing packets, that indicative of program information, that indicative of current time. The control data for multiplexing packets are assigned for correctly identifying a video/audio data of a plurality of services being packetized under a time-sharing manner and other purposes.
The multiplexing part 11 outputs the control data and the video/audio data ES11, ES12, ES13, and ES14 under a time-sharing manner, each consisting of packetized data having a fixed length.
A scrambler 12 scrambles the outputted packets using a scramble-key provided by a scramble-key control part 16. The transport stream TS1 being scrambled is modulated with a modulating part 14 and sent out to audiences via the broadcasting satellite 4.
The scramble-key used at the scrambler 12 is encrypted with the control data generating part and made to be Entitlement Control (hereinafter referred to as ECM) data. In other words, ECM data further encrypting the key used for de-scrambling is generated. The multiplexing part 11 carries out packetization including the ECM data.
1.3. Structure of the Transport Streams
As shown in FIG. 3, video data ES (V) 1 and audio data ES (A) 1 of the service SV11, video data ES (V) 2 and audio data ES (A) 1 of the service SV12, video data ES (V) 3 and audio data ES (A) 3 of the service SV13, and video data ES (V) 4 and audio data ES (A) 4 of the service SV14 are multiplexed in the transport stream TS1 generated by the transmitter depicted in FIG. 2.
In addition, control data NIT, PAT, PMT1, PMT2, PMT3 and PMT4 are further multiplexed therein. Audio data and video data of the service SV11, SV12, SV13 and SV14 can be separated respectively by using these control data.
Further, control data for the scramble-key CCM1, ECM2, ECM3 and ECM4, control data indicative of program information EIT1, EIT2, EIT3 and EIT4, and control data for current time TDT and the like are multiplexed therein. Although, none of them are shown in the drawing, more control data are multiplexed in the transport stream.
Packetization of the control data, is carried out in the sequence of a line 18a depicted in FIG. 3. In other words, packetization of these control data is carried out by the following sequence: the control data NIT, PIT, PMTs EITs, ECMs, video data ESs (V) and audio data ESs (A). Upon completing the first round ends at the audio data ES (A) 4, further rounds of packetization are carried out repeatedly (see a line 18b).
A basic structure of the packetized data is depicted in FIG. 4. Both the control data and the video/audio data being packetized have the structure as depicted in FIG. 4. PIDs are assigned to the forefront of each packetized data. PIDs are the references, which are uniquely assigned to each of the packetized data to distinguish each packetized data from other packetized data. The data representing contents are object data being packetized (e.g. the control data, video/audio data and the like).
A relationship among the control data PAT, PMT1, PMT2, PMT3, PMT4 and video/audio data ESs in each of the services is depicted in FIG. 5. For example, a PID 502 is assigned to video/audio data 500 being packetized, and the video/audio data 50 in the service SV12 being encrypted. Although, Just one packet is illustrated in the drawing as a typical illustration thereof, the video/audio data 500 is sent in a plurality of packets as a result of carrying out time sharing processing. Similarly, a PID 506 is assigned to ECM data 504 being packetized for generating a descramble-key, which descrambles the scramble on the video/audio data 500.
The packet ID of the video/audio data 500 in the service SV12 and that of the ECM data 504 are recorded in the control data PMT2. In view of this, the packet IDs of the video/audio data 500 in the service SV12 and the ECM data 504 can be identified by obtaining the contents of the control data PMT2. A PID 512 is assigned to the control data PMT2 being packetized as well. Although, just one packet is illustrated in the drawing as a typical illustration thereof, the control data PMT2 is also sent in a plurality of packets as a result of carrying out time sharing processing.
A packet ID of the control data PMT2 is recorded in the control data PAT. In this way, the packet ID of the control data PMT2 in the service SV12 can be identified by obtaining the contents of the control data PAT. A PID 522 is assigned to the control data PAT being packetized as well. Packet IDs of the control data PMT1, PMT2, PMT3 and PMT4 in the services SV11, SV12, SV13 and SV14 multiplexed in the transport stream TS1 are recorded in the control data PAT.
Control data, video/audio data, each packetized and related one another are sent through transport streams. It is therefore, necessary to obtain the control data PAT in order to identify the services multiplexed in the transport streams. In this way, the packet ID of the control data PAT is previously set at a fixed value such as (0X0000).
Information such as transmission parameters of the transport streams TS1, TS2 and TS3 (their frequencies or the like) and which of the services being multiplexed into which of the transport stream is recorded in the control data NIT (see FIG. 6). In this way, it is possible to identify a specific service is multiplexed into which of the service(s). Packet ID of the control data NIT is recorded in the control data PAT.
1.4. Configuration of the Receiver
FIG. 8 outlines configuration of a receiver. In the receiver, a desired transport stream is selected by a tuner 22 and scrambled transport stream is descrambled with a descrambler 24, then data concerned with the desired service contained in the descrambled transport stream is separated therefrom with a transport decoder 26. The microprocessor (hereinafter referred to as MPU) 28 sends an ECM obtained to an IC card 30 and receives the a scramble-key restored by the IC card30. The MPU 28 then sets the scramble-key in the descrambler 24 The video/audio data ES can thereby de descrambled.
The MPU 28 sets the packet ID of the video/audio data ES in the desired service into the transport decoder 26. The transport decoder 26 thereby outputs the video/audio data ES of the service. When the packet ID of the control data is set in the transport decoder 26, the control data thus separated is supplied to the MPU 28.
An operation of the receiver, which currently receives the service SV33, contained in the transport stream TS3, and receives a command to switch it to the service SV12 included in the transport stream TS1 will be described herein. The MPU 28 controls the transport decoder 26 to obtain the control data NIT (i.e., by setting a PID of the control data NIT into the transport decoder 26). The description in the control data tells that the service SV12 is multiplexed in the transport streamTS1 (see Fig. G).
In response to the description, the MPU 28 controls the tuner 22 to receive the transport stream TS1. Further, the receiver acquires the PAT and PMT 2 by controlling the transport decoder 26, and the packet IDs of both the video data ES (V) 2 and the audio data ES (A) 2 in the desired service SV12, and packet IDs of their ECMs (see an arrows α and β in FIG. 5).
Next, the video data ES (V) 2 and the audio data ES (A) 2 of the desired service SV12 are outputted from the transport decoder 26 by setting these packet IDs in the transport decoder 26. In parallel with this, the MPU 28 acquires the scramble-key by sending the ECM obtained from the transport decoder 26 to the IC card 30 and sets this in the descrambler 24. Descrambled video data ES (V) 2 and audio data ES (A) 2 can thereby be obtained. Changeover of the received service is performed as described above.
2. Outline of Satellite Broadcasting System Realizing Interactive Operations
2.1. Outline of the System
Next, the outline of the satellite broadcasting system realizing interactive operations will be described. Here, a system, which is realized and is proposed by the applicant, is described as an example.
The layout of the transmitter is the same as that of shown in FIG. 2. However, it differs in that control data generating part 6 also generates navigation data, to be described.
FIG. 8 shows the data structure of a transport stream that is sent from the transmitter in the broadcasting system realizing interactive operations. In the drawing depicts the video data ES (V) 11, ES (V) 12 and ES (A) 11, ES (A) 12 in the service 11, the video data of other services and audio elementary streams for audio data are omitted. The difference from the data structure of FIG. 3 is that two (2) video/audio ESs are contained in a single service SV11. Interactive changeover of these two (2) video/audio ESs can be performed by operation of the operator in accordance with the navigation data NVT1 and NVT 2 both forming control data for realizing interactive operations. The receiver is designed so as to alter the auxiliary display in an interactive manner by using the navigation data NVT1 and NVT2.
FIG. 9 shows the contents of control data PMT1 in the service SV11. The control data PMT1 describes the packet ID of each content (vide, audio, navigation data) and the packet ID of the ECM data for obtaining the key for descrambling the contents. Furthermore, since all of the video, audio, and navigation data have a plurality of contents, the content that is to be initially outputted is given as entry-contents. The packet ID of this control data PMT itself is in “0X0011”.
FIG. 10 shows contents of the control data PAT. In the control data PAT, there are given the packet IDs of the PMTs relating to the services SV11, SV12, SV13 and SV14 these are multiplexed on the transport stream TS1. In this way, it is possible to identify the packet ID of the service SV11 is in “0X0011”. It should be noted that the packet ID of the control data PAT itself is fixed as “0X0000”.
FIGS. 11, and 12 show contents that are recorded in the navigation data NVT1 and NVT2. The same contents of this set of navigation data NVT1 and NVT2 are repeatedly sent at predetermined intervals. Interactive alteration of the service contents is performed as shown in FIGS. 13 through 16 in response to the operation of operator using the navigation data NVT1 and NVT2.
An image depicted in FIG. 14 is displayed when the operator presses a key to move the cursor downward under the display shown in FIG. 13. In other words, the reference part on the display “Order to Osaka center” shifts to the display “Tokyo center”. Further depress of the downward key will shift the reference part on the display to “Go to the clothing store” as depicted in FIG. 15. The contents of the service is changed into a Tele-shopping offering clothing items as depicted in FIG. 16 when the operator presses a selection button under the condition.
Such interactive operations described above are realized in accordance with the navigation data forming control data for interactive operations.
Although, the services in moving pictures are selected in accordance with the navigation data in the above-described operations, services in still images can also be selected. In that case, a desired still image is displayed as a result of selection performed in accidence with the control of the navigation data so as to select the desired still image out of a plurality of still images being sent repeatedly as one complete service.
3. Outline of Digital Video Recording/Reproduction Apparatus
In the contrary, digital video recording/reproduction apparatuses recording satellite broadcasting as digital data have been proposed (in Japanese patent application No. H10-367155 and related applications filed invented by the applicant of this application). Other recording/reproduction apparatuses capable of performing cue and review in accordance with data for special playback stored separately from data for normal playback have also been proposed (disclosed in Japanese Laid Open Publication No. H06-284378 and H08-214261).
However, the prior art even not aware problems laid between the interactive operations performed in digital broadcasting and the digital video recording/reproduction apparatus for recording thereof.
The applicant has already proposed a technique by which recording and reproduction are performed while maintaining interactive capability thereof. The technique is superior in a view of solving the problems occur when the interactive operations performed in receiving digital broadcasting are also carried out during the recording and reproduction. The technique, however, neither pointing out the problems in the interactive operations occurred by confusion therein nor solving the problems.
Generally, bandwidth for recording data for special playback is limited, therefore, it is expected that one of no data for interactive operations are recorded as the data for special playback and only a small amount of data are recorded even data recording is allowed. Under the circumstances, the following problems are observed when digital data for realizing interactive operations are recorded and reproduced.
For example, the problems will be described using a service having an interactive capability depicted in FIG. 17. In the drawing, time travels on the left to the right hand side thereof. A display of “Quiz regarding to lions” forming an image for performing operations is displayed when an image of a lion is displayed on the screen. A quiz on lions is displayed on the screen in accordance with the navigation data (the control data for interactive operations) when the operator selects the display of “Quiz regarding to lions” with buttons on the remote controller or the like.
Similar operations can be carried out upon displaying a display of “Quiz regarding to elephants” forming an image for performing operations as a result of revising its version of the navigation data so as to display an image of an elephant. Such operations can be realized not only when the apparatus receives data but also at the time of performing normal playback. Carrying out recording so as to contain the navigation data does this.
However, the display of “Quiz regarding to lions” forming the image for performing operations undesirably remains on the screen regardless of sudden change of images when playback is performed in cue because no control data for realizing interactive operations are obtained. In other words, countermeasures for preventing such undesirable display need to be taken in consideration of performing playback in cue. Similar problems occur during the special playback such as review or the like.
Other problems described below arise when a service capable of selectively displaying a plurality of still images under interactive basis. In such service, the creator of the service may control still images in accordance with the control data for performing interactive operations, the still images being displayed on the screen responding to inputs of the operator. For example, in a service by which provide quiz, a control in which a certain still image is displayed can be carried out only when correct answers to the quiz are inputted.
Images containing still images indicative of the correct answer, however, are unexpectedly displayed when special playback such as cue and the like is performed because no interactive control (or insufficient interactive operation) is carried out. These problems need to be solved in order to record and reproduce services for performing interactive operations in view of considering special playback.
Further, there is a high probability of causing the undesirable display as a result of performing only control commands in the interactive command regardless of suspension of the image for performing operations when playback is in pause during the reproduction of a service for performing interactive operations. This happens especially on commands performed depending on the time. On the contrary, there are some commands preferably continuing even in pause such as communication command between the apparatus and external apparatus(es). In such a view, problems described above for recording/reproduction of the services for performing interactive operations need to be solved in view of considering pause of the playback.